linux-kernel - Re: [PATCH v4 3/5] selftests/resctrl: Split validate_resctrl_feature

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Date: Mon, 5 Feb 2024 14:24:01 +0100
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC: <fenghua.yu@...el.com>, Reinette Chatre <reinette.chatre@...el.com>,
	<shuah@...nel.org>, <linux-kselftest@...r.kernel.org>, LKML
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/5] selftests/resctrl: Split
 validate_resctrl_feature_request()

On 2024-02-05 at 14:41:30 +0200, Ilpo Järvinen wrote:
>On Mon, 5 Feb 2024, Maciej Wieczor-Retman wrote:
>
>> validate_resctrl_feature_request() is used to test both if a resource is
>> present in the info directory, and if a passed monitoring feature is
>> present in the mon_features file.
>> 
>> Refactor validate_resctrl_feature_request() into two smaller functions
>> that each accomplish one check to give feature checking more
>> granularity:
>> - Resource directory presence in the /sys/fs/resctrl/info directory.
>> - Feature name presence in the /sys/fs/resctrl/info/L3_MON/mon_features
>>   file.
>> 
>> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
>> ---
>> Changelog v4:
>> - Roll back to using test_resource_feature_check() for CMT and MBA.
>>   (Ilpo).
>> 
>> Changelog v3:
>> - Move new function to a separate patch. (Reinette)
>> - Rewrite resctrl_mon_feature_exists() only for L3_MON.
>> 
>> Changelog v2:
>> - Add this patch.
>> 
>>  tools/testing/selftests/resctrl/cmt_test.c  |  2 +-
>>  tools/testing/selftests/resctrl/mba_test.c  |  2 +-
>>  tools/testing/selftests/resctrl/mbm_test.c  |  6 ++--
>>  tools/testing/selftests/resctrl/resctrl.h   |  3 +-
>>  tools/testing/selftests/resctrl/resctrlfs.c | 33 +++++++++++++--------
>>  5 files changed, 28 insertions(+), 18 deletions(-)
>> 
>
>> diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c
>> index dd5ca343c469..c1157917a814 100644
>> --- a/tools/testing/selftests/resctrl/cmt_test.c
>> +++ b/tools/testing/selftests/resctrl/cmt_test.c
>> @@ -170,7 +170,7 @@ static int cmt_run_test(const struct resctrl_test *test, const struct user_param
>>  static bool cmt_feature_check(const struct resctrl_test *test)
>>  {
>>  	return test_resource_feature_check(test) &&
>> -	       validate_resctrl_feature_request("L3_MON", "llc_occupancy");
>> +	       resctrl_resource_exists("L3");
>
>This not correctly transformed.

Oops, sorry, I'll fix it for the next version.

>
>> +/*
>> + * resctrl_mon_feature_exists - Check if requested monitoring L3_MON feature is valid.
>> + * @feature:	Required monitor feature (in mon_features file).
>> + *
>> + * Return: True if the feature is supported, else false.
>> + */
>> +bool resctrl_mon_feature_exists(const char *feature)
>> +{
>> +	char *res;
>> +	FILE *inf;
>> +
>>  	if (!feature)
>> -		return true;
>> +		return false;
>>  
>> -	snprintf(res_path, sizeof(res_path), "%s/%s/mon_features", INFO_PATH, resource);
>> -	inf = fopen(res_path, "r");
>> +	inf = fopen("/sys/fs/resctrl/info/L3_MON/mon_features", "r");
>
>This became less generic? Could there be other MON resource besides L3 
>one? Perhaps there aren't today but why remove the ability give it as a 
>parameter?

During v2 discussion [1] Reinette made me realize this functionality only
interfaces with L3_MON/mon_features file and the 'resource' parameter isn't
needed. The 'mon_features' file is only mentioned for L3_MON and I don't know of
any plans for other MON resources so I assumed it doesn't need to be generic.

But sure, I can make it use a parameter if Reinette doesn't mind.

[1] https://lore.kernel.org/all/2o7adr2cos6qcikcu7oop4ss7vib2n6ue33djgfeds3v6gj53f@uu45lomrp5qv/

>
>
>-- 
> i.
>

-- 
Kind regards
Maciej Wieczór-Retman